小鸟的英语单词是"bird"。它的来源是源自古英语的"brid"，这个词的意思是“小鸟”。

例句：

I saw a bird outside my window this morning. (我今天早上在窗外看到一只小鸟。)

The bird was singing a beautiful song. (那只小鸟在唱着一首美丽的歌。)

The bird has a colorful feather. (那只小鸟有五颜六色的羽毛。)